169 research outputs found
Distribution in France of a naturalized pel, the Siberian Chipmunk (Tamias sibiricus)
Apparu dans les animaleries de diffĂ©rents pays europĂ©ens au cours des annĂ©es 1960, le Tamia de SibĂ©rie (Tamias sibiricus), SciuridĂ© originaire d'Asie, a Ă©tĂ© lĂąchĂ© dans la nature Ă la fin des annĂ©es 1970. Une enquĂȘte nationale lancĂ©e en 2000 auprĂšs des agents de l'Office National des ForĂȘts, complĂ©tĂ©e par diverses autres informations, a permis de recenser sept populations implantĂ©es dans des forĂȘts pĂ©riurbaines et des parcs urbains de la RĂ©gion Ile-de-France, et trois populations dans des forĂȘts de la RĂ©gion Picardie. Certaines de ces populations comptent actuellement plusieurs milliers d'individus. Leur prĂ©sence est liĂ©e Ă l'introduction dĂ©libĂ©rĂ©e d'un nombre inconnu, mais probablement rĂ©duit dans chaque cas, d'individus dont la compagnie lassait leurs propriĂ©taires. Seule la population situĂ©e Ă Villers-Carbonnel (Picardie) provient d'une trentaine de lamias Ă©chappĂ©s d'un Ă©levage. Sur certains sites, la vitesse de colonisation est comprise entre 200 et 250 m par an au cours des premiĂšres dĂ©cennies ayant suivi l'introduction. La population de la forĂȘt de Meudon (Hauts-de-Seine) a fait l'objet de dĂ©nombrements hebdomadaires, sur itinĂ©raire-Ă©chantillon, de mars 2000 Ă fĂ©vrier 2004. En 2002, 15 adultes marquĂ©s avec une bague auriculaire identifiable Ă distance ont Ă©tĂ© suivis d'avril Ă octobre. Ces observations et celles provenant de travaux effectuĂ©s sur son aire d'origine, dans d'autres pays europĂ©ens ou en captivitĂ©, permettent de cerner ses principaux traits d'histoire de vie et de disposer d'Ă©lĂ©ments permettant d'analyser sa propension Ă devenir une espĂšce envahissante en France.The Siberian Chipmunk (Tamias sibiricus) has been sold in pet shops of various European countries since the 1960âs, and voluntarily released in the wild since the 1970âs. In 2000, I held a national inquiry of the wardens of the National Forests Office. The results of this survey, supplemented by other sources, showed the presence of seven populations established in suburban forests and in urban parks of the RĂ©gion Ile-de-France, and of three populations established in forests of the RĂ©gion Picardie. Some of these populations number several thousands of individuals. Their origin may be related to deliberate introduction of a presumably low number of individuals, introduced by owners. The only exception is the Villers-Carbonnel (Picardie) population, where about 30 individuals escaped from a pet shop. Some populations seem to spread out at a rate of 200 to 250 m per year, at least during the first decades following their introduction. Weekly censuses on strip-transects were done on one population (Meudon, Hauts-de-Seine), between March 2000 and February 2004. In 2002, 15 adults were marked with ear tags and followed between April and October. These observations, along with observations from other studies in the species native area, in other European countries, or in captivity, allowed me to list the principal features of the life history of T. sibiricus, and to discuss the potential of this introduced squirrel to become an invasive species on the French territory
Une gamme d'ßles de référence, un atout majeur pour l'évaluation de programmes de restauration dans l'archipel de Kerguelen
The Kerguelen Archipelago is constituted by a main island (6 500 km2) and about sixty
secondary islands (1-200 km2). Somee of these islands are pristine, while some others have
been colonized by introduced plants, invertebrate species and, in some cases, by one or several
alien mammals. Programs of ecological restoration began in 1992 on three islands,
Verte I., Guillou I. and Cochons I. (respectively 150, 145 and 165 ha) damaged by the presence
of mammals (rabbits, rabbits-cats-mice, rabbits-mice). The management action was the
eradication of rabbits by poisoning. Due to the existence of reference islands (with or without
introduced mammals), and of control islands (presence of rabbits), the Kerguelen Archipelago
offers an unusual opportunity to distinguish the effects of the management intervention from
those of other factors. For example, synchronised vegetation monitoring of habitats on a control
island (CimetiĂšre I., colonized by rabbits) has shown the role of this mammal in controlling
one introduced Asteraceae (Taraxacum officinale). After rabbit eradication, this plant
drastically increased in cover on the three experimental islands. Moreover, results from
Mayes I. (without herbivores) and from the 4 other islands studied, emphasized the impact of
the present climatic changes on the evolution of plant communities. This factor explains most
of the decrease in cover of several native species, especially Acaena magellanica, with the
timing of Dandelion's success linked to open land appearance. These observations confirmed
the value of contemporary reference sites to analyze the advantages of restoration programs
and to conduct future actionsL'archipel de Kerguelen est constitué d'une ßle principale (6 500 km2) et d'une soixantaine
d'Ăźles secondaires (1-200 km2). Certaines sont totalement indemnes d'espĂšces introduites,
d'autres ont été colonisées par des espÚces végétales et des invertébrés allochtones, et
d'autres encore sont occupées, de plus, par un ou plusieurs mammifÚres introduits. Un programme
de restauration écologique concernant trois ßles (145 à 165 ha) dégradées par la présence de mammifÚres (lapin, lapin-souris, lapin-chat-souris) a été initié en 1992 par éradication
du lapin. Par la présence d'ßles de référence (sans herbivore introduit) et d'ßles témoin
(avec lapin), l'archipel de Kerguelen offre une situation exceptionnelle permettant de distinguer
les effets de l'intervention de ceux d'autres facteurs. Le suivi synchronique de la végétation
de différentes ßles a permis de mettre en évidence, par exemple, le rÎle du lapin sur le
contrÎle d'une Astéracée introduite (Taraxacum officinale) et l'importance des changements
climatiques sur les trajectoires d'évolution des communautés végétales. Ces observations ont
confirmĂ© l'intĂ©rĂȘt de disposer de rĂ©fĂ©rences contemporaines pour analyser les bĂ©nĂ©fices
d'opérations de restauration et pour orienter les actions à veni
Résilience des communautés insulaires subantarctiques : facteurs influençant la vitesse de restauration écologique aprÚs éradication de mammifÚres introduits
Cattle were introduced to Amsterdam Island in 1871 and rabbits to the Kerguelen Archipelago
in 1874. These herbivorous mammals caused severe damage to these terrestrial ecosystems.
Two ecological restoration programs were implemented: cattle eradication from the
southern part of Amsterdam Island (55 km2) in 1988 and rabbit eradication from three small
islands (145 to 165 ha) at Kerguelen from 1992. On Amsterdam Island, in a temperate climate,
the recovery of vegetation depended on the degree of damage caused to the environment
by cattle. On the Jess eroded organic soils, recovery of native vegetation (e. g. Poa novarae,
Blechnum penna-marina) was observed 10 years after cattle eradication. Conversely, on the
thin and eroded mineral soils, an irreversible level of disturbance occurred: vegetation recovery
was very slow and introduced plant species (e.g. Holcus lanatus) remained dominant
while the cover of autochtonous species (Scirpus nodosus, Blechnum penna-marina)
increased very slowly. Due to the cooler climate, ecological restoration processes were slower
at Kerguelen than at Amsterdam Island. For some autochtonous species, such as Pringlea
antiscorbutica and Azorella selago , presence of refuge areas on cliffs inaccessible to rabbits
was important for colonization after rabbi! eradication. Vegetation changes depended greatly
on the climatic changes recently recorded (characterised by a slight increase in temperature
and more frequent summer drought). In contrast to the autochtonous species, most of the alien
plants ( Taraxacum officinale, Senecio vulgaris...), originating from temperate regions, were
favoured by these climatic changesL'introduction de bovins en 1871 sur l'Ăźle Amsterdam et de lapins en 1874 dans l'archipel
de Kerguelen a eu un impact considérable sur les écosystÚmes terrestres. Deux programmes
de restauration écologique ont été mis en place, l'un en 1988 par élimination des bovins
de la partie sud de l'ßle Amsterdam (55 km2), le second à partir de 1992 par éradication des lapins sur trois ßles (1,45 à 1,65 km2) à Kerguelen. Sur l'ßle Amsterdam, les capacités et la
vitesse de restauration des communautés dépendent du niveau de la perturbation des milieux
engendrée par les bovins. Alors qu'une dizaine d'années a suffi à la restauration des communautés
végétales sur certains secteurs dont les sols étaient peu dégradés, l'évolution est lente
et les espĂšces introduites restent dominantes sur de larges secteurs oĂč l'Ă©rosion du sol atteint
un seuil d'irréversibilité. A Kerguelen, les processus de restauration, plus lents, ont été de
plus fortement influencés et limités par les changements climatiques récents (sécheresse estivale
de plus en plus fréquente) qui bénéficient aux espÚces introduites, originaires de régions
plus tempérées, et pénalisent les espÚces locales pour lesquelles ces conditions sont entiÚrement
nouvelle
Impact des changements climatiques et de la fréquentation humaine sur la biodiversité des ßles subantarctiques françaises
Lâinvasion des Ă©cosystĂšmes par des espĂšces exotiques constitue, en conjonction avec les changements climatiques, une des plus grandes menaces pour la biodiversitĂ© mondiale, aprĂšs la destruction des habitats. MĂȘme dans les rĂ©gions antarctiques et subantarctiques, des espĂšces Ă©trangĂšres Ă la faune et Ă la flore locales ont Ă©tĂ© introduites dĂšs la fin du 18e siĂšcle. La majoritĂ© de ces introductions sont associĂ©es Ă la frĂ©quentation humaine et aux visites des navires. Par ailleurs, comme le prĂ©disent la plupart des modĂšles, les rĂ©gions de hautes latitudes sont les plus sensibles aux changements climatiques. Les observations faites Ă Kerguelen confirment cette tendance et attestent de lâimpact dĂ©jĂ bien visible des augmentations de tempĂ©rature (1,3°C depuis le milieu des annĂ©es 1960) et des dĂ©ficits hydriques estivaux rĂ©currents ces derniĂšres annĂ©es. Avec ces changements climatiques rapides, une augmentation du nombre dâintroductions dâespĂšces et de leur succĂšs dâĂ©tablissement est attendue, de mĂȘme que la fragilisation de la faune et la flore locales, dâoĂč de notables consĂ©quences prĂ©visibles quant Ă la biodiversitĂ© de ces rĂ©gions trĂšs particuliĂšres.Biological invasions, in connection with climate changes, are amongst the most significant threats to biodiversity worldwide. Even in antarctic and subantarctic regions, alien species arrived since the end of the 18th century. Most of these introductions are obviously associated with human activities and ship landings. Otherwise, as predicted by many global circulation models, rates of warming are expected to be stronger at higher latitudes. Our study on the Kerguelen Islands confirms this trend and demonstrates that the effects of warming (+ 1.3°C since the mid 1960s) and summer droughts on plants and invertebrates are now visible. With climate change occurring rapidly, both the numbers of introductions and the success of colonisation by alien species are likely to increase, with as consequence subsequent impacts on the entire ecosystem
House mouse colonization patterns on the sub-Antarctic Kerguelen Archipelago suggest singular primary invasions and resilience against re-invasion
Starting from Western Europe, the house mouse (Mus musculus domesticus) has spread across the globe in historic times. However, most oceanic islands were colonized by mice only within the past 300 years. This makes them an excellent model for studying the evolutionary processes during early stages of new colonization. We have focused here on the Kerguelen Archipelago, located within the sub-Antarctic area and compare the patterns with samples from other Southern Ocean islands
New challenges in solar architectural innovation
Among the centuryâs main challenges, climate change and the need for energy sources diversification are of great importance. In this context, renewable energies undoubtedly have an important role to play. Photovoltaic (PV) electricity is especially well suited to face these energy challenges. It is now established that the low thin film photovoltaic panels production costs will allow, even in continental climate, to reach low electricity cost, providing easy installation, public acceptance and high reliability. However, architectural considerations are often neglected in the current integration of PV panels. Taking into consideration specific architectural aspects like the surface appearance and the colour of the PV modules can become the key for the successful development of new, well integrated solar systems. To achieve this goal, our team, within the Archinsolar [1] project framework, works on the development of new generation of photovoltaic elements based on silicon thin films technologies (amorphous and micromoph). These new elements will be ultra-reliable and manufacturable at a very low cost, allowing a good architectural integration, respectful of the environment, landscape and built environment. Genera
Innovative Solution for Building Integrated Photovoltaics
Among the main challenges of our century, the climate change and the need of diversification of the energy sources are of most importance. Renewable energies undoubtedly have an important role to play, photovoltaic (PV) electricity being especially well suited to face these energy challenges. However, the current integration of PV panels often comes without architectural consideration. In this context, the Archinsolar project [1] aims to develop a new generation of photovoltaic elements based on silicon thin films technologies (amorphous and micromorph), ultra-reliable and manufacturable at a very low cost, allowing a unique architectural integration, respectful of the bui lt environment and overall landscape. Here we will present our new developments on innovative PV elements including colored PV panels and a solar tile using a composite back-structure
Seabird Modulations of Isotopic Nitrogen on Islands
The transport of nutrients by migratory animals across ecosystem boundaries can significantly enrich recipient food webs, thereby shaping the ecosystemsâ structure and function. To illustrate the potential role of islands in enabling the transfer of matter across ecosystem boundaries to be gauged, we investigated the influence of seabirds on nitrogen input on islands. Basing our study on four widely differing islands in terms of their biogeography and ecological characteristics, sampled at different spatial and temporal intervals, we analyzed the nitrogen isotopic values of the main terrestrial ecosystem compartments (vascular plants, arthropods, lizards and rodents) and their relationship to seabird values. For each island, the isotopic values of the ecosystem were driven by those of seabirds, which ultimately corresponded to changes in their marine prey. First, terrestrial compartments sampled within seabird colonies were the most enriched in ÎŽ15N compared with those collected at various distances outside colonies. Second, isotopic values of the whole terrestrial ecosystems changed over time, reflecting the values of seabirds and their prey, showing a fast turnover throughout the ecosystems. Our results demonstrate that seabird-derived nutrients not only spread across the terrestrial ecosystems and trophic webs, but also modulate their isotopic values locally and temporally on these islands. The wealth of experimental possibilities in insular ecosystems justifies greater use of these model systems to further our understanding of the modalities of trans-boundary nutrient transfers
British Red Squirrels Remain the Only Known Wild Rodent Host for Leprosy Bacilli
<p>Eurasian red squirrels (Sciurus vulgaris) in the British Isles are the most recently discovered animal reservoir for the leprosy bacteria Mycobacterium leprae and Mycobacterium lepromatosis. Initial data suggest that prevalence of leprosy infection is variable and often low in different squirrel populations. Nothing is known about the presence of leprosy bacilli in other wild squirrel species despite two others (Siberian chipmunk [Tamias sibiricus], and Thirteen-lined ground squirrel [Ictidomys tridecemlineatus]) having been reported to be susceptible to experimental infection with M. leprae. Rats, a food-source in some countries where human leprosy occurs, have been suggested as potential reservoirs for leprosy bacilli, but no evidence supporting this hypothesis is currently available. We screened 301 squirrel samples covering four species [96 Eurasian red squirrels, 67 Eastern gray squirrels (Sciurus carolinensis), 35 Siberian chipmunks, and 103 Pallas's squirrels (Callosciurus erythraeus)] from Europe and 72 Mexican white-throated woodrats (Neotoma albigula) for the presence of M. leprae and M. lepromatosis using validated PCR protocols. No DNA from leprosy bacilli was detected in any of the samples tested. Given our sample-size, the pathogen should have been detected if the prevalence and/or bacillary load in the populations investigated were similar to those found for British red squirrels.</p
Multiancestry analysis of the HLA locus in Alzheimerâs and Parkinsonâs diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes
Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinsonâs disease (PD) and Alzheimerâs disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased AÎČ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues
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